-5x vs 7x zoom
-Menu controls are different. I didn't like the WX9 controls when I tried it out - bit of a learning curve there. The Wx10 is more simple to use in my opinion.
-Battery life of the Wx9 is weaker
Obviously the wx10 is the nearer model so the wx9 is now heavily discounted. Still $110 is a lot. Depends on whether any of the above really concern you. I would definitely try out the wx9 first to see if the menu controls are to your liking.